The Annacis Island Wastewater Treatment Plant (AIWWTP) is undertaking a critical infrastructure upgrade involving the replacement of an aging 500 mm diameter Process Water Drain (PWD) pipe. The existing carbon steel pipe, running through an operational gallery, has reached the end of its service life and exhibits signs of corrosion, leaks, and structural fatigue. In addition, the Gravity Thickener overflow carbon steel piping (TOF) for three thickeners has reached the end of its service life and requires replacement. The TOF piping is underground and will require soil excavation and trenching.  Upon completion of the TOF piping replacement work the entire area surrounding the five gravity thickeners is paved with asphalt under this contract. Details refer to Section 011100 Summary of Work and Section 011110 General Requirements for a detailed description of the Work.